JPH02285027A - Water circulating device - Google Patents

Abstract

PURPOSE:To effectively cool the weld zone even when bubbles are generated in a space by providing a water injection pump above the open side of the space for circulating cooling water and injecting water from the closed side of the space toward the open side. CONSTITUTION:A cooling water pipe 8 is fixed to a recirculation inlet nozzle 1 of the water circulating device through stoppers 14a and 14b. The water injection pump 10 is connected to the cooling water pipe 8, and an injection nozzle 7 is formed at the tip opening of the pipe. When water is injected from the nozzle 7, the water in a cylindrical space 6 is sucked from a suction pipe 11 provided at the closed side of the space 6, mixed with the water supplied from the cooling water pipe 8 at a throat 12 and discharged via a diffuser 13. The weld zone 2 and its vicinity are heated by a heater 9 while cooling water flows in the space 6 to produce a specified temp. distribution, and residual stress is effectively improved.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a water circulation device, and more particularly to a device for circulating and cooling water in a narrow space in order to improve residual stress in a double metal pipe or the like. .

[Conventional technology]

When improving the residual stress of a double metal pipe with a narrow space formed by a thermal sleeve, such as a nozzle placed in a pressure vessel, water is circulated within the narrow space to cool the inside of the weld while cooling the outside of the weld. It is necessary to heat the weld and create a predetermined temperature difference distribution in and around the weld.

Examples of conventional water circulation devices of this type are shown in Figures 9 and 1O, in which l is the recirculating water inlet nozzle, 2 is the weld, 3 is the safe end, 4 is the base weld, 5 1 is a thermal sleeve, 6 is a space (narrow part), 9 is a heating means, 18 is a cooling water jet nozzle, and 19 is a cooling water pipe. In this water circulation device, water is jetted into the space 16 from a cooling fountain nozzle 18 installed on the open side of the space 6 to generate a steady flow reaching the closed side of the space 6, and then, for example, induction heating is performed. (hereinafter referred to as the blowing method) is a method of heating the outside of the welding part 6 by a heating means 9 such as (Japanese Patent Application Laid-open No. 143221/1982). In addition, in FIG. 10, the cooling water vibrator 19 is branched, Cooling water spout nozzle 1, one of which spouts water into space 6
8 and the other constitutes a suction nozzle 20, which is different from the water circulation apparatus shown in FIG. This water circulation device uses a method (hereinafter referred to as a blow-in and suction method) in which a steady flow is achieved in the space 6 by means of a cooling water jet nozzle 18 and a suction nozzle 20.
Publication No. 397) [Problems to be Solved by the Invention] In the conventional water circulation device using the above-mentioned method, sufficient consideration is not given to the upward flow caused by the generation of air bubbles in the space 6, and therefore a large amount of cooling water is used when air bubbles are generated. There was a problem in that the liquid had to flow into the space 6.

When a large amount of cooling water flows into the space 6, in the water circulation system shown in FIG. Receive a force that moves you away. Therefore, in the case of a nozzle installed in a place where access is difficult, there is a problem in that it is difficult to fix the cooling water jet nozzle 18, and the cooling water jet nozzle 18 moves, making it difficult to perform an effective cooling operation. Ta.

In the water circulation system shown in FIG. 10, the installation of the suction nozzle 20 alleviates the problem of movement of the cooling water jet nozzle during one day when water is jetted into the space 6.

However, the cooling water injected from the cooling water jetting nozzle 18 does not reach the base welded portion 4, but instead passes through the seat and flows toward the suction nozzle 20, making effective cooling difficult.

An object of the present invention is to solve the above-mentioned problems of the prior art, to be able to effectively cool a welded part with a small amount of injection even when air bubbles are generated in a space, and to make it possible to effectively cool a welded part with a small amount of injection. The object of the present invention is to provide a water circulation device that does not require fixing.

[Means to solve the problem]

The above purpose is to provide a water injection pump at the upper part of the open side of the space (narrow part) in which cooling water is circulated, which injects water in the direction from the outside of the narrow part, that is, from the closed side of the space to the open side. This is achieved by

[Effect]

Cooling water from the water injection pump installed at the upper part of the open side of the space is injected from the closed side of the space (narrow part) toward the open side, from the lower part of the open side to the lower part of the closed side, and then to the upper part of the closed side. and flows to the upper part of the open side. As a result, the direction of the buoyancy of the bubbles in the water matches the flow of the cooling water, and the amount of cooling water required to extract the generated bubbles from the space is reduced.

Since the amount of cooling water injected into the space is reduced, the momentum of the water is small, and since the cooling water from the water injection pump is injected from the closed side of the space to the open side, the amount of water is reduced based on the momentum of the water. The reaction that the injection pump receives is in the direction from the open side of the space toward the closed side, and there is no particular need to fix the injection nozzle.

〔Example〕

Embodiments of the present invention will be described below based on the drawings.

FIG. 1 is a sectional view showing an embodiment of the water circulation device of the present invention;
FIG. 2 is an enlarged sectional view of the water injection pump in FIG. 1.

The safe end 3 and the recirculating water inlet nozzle 1 are connected through a weld 2, the safe end 3 and the thermal sleeve 5 are connected through a base weld 4, and the recirculating water inlet nozzle 1 and the thermal sleeve 5 are connected through a base weld 4. A cylindrical space (narrow part) 6 is formed between the two. A cooling water vibrator 8 is fixed to the recirculation inlet nozzle 1 on a surface perpendicular to a surface parallel to the outer peripheral surface of the thermal sleeve 5 via movement prevention stands 14a and 14b.

A water injection pump 14 is connected to the opening at the tip of the cooling water vibrator 8 .

The water injection pump 14 is connected to a cooling water vibrator 8 as shown in FIG. 13 is fixed to the outer peripheral surface of the thermal sleeve 5 via a movement prevention stand 14c. Deaf user 1
A suction pipe 11 is provided on the side opposite to the direction in which water is ejected from the space 6 , that is, on the closed side of the space 6 , and an internal flow path of the suction pipe 11 communicates with the throat 12 of the diffuser 13 .

In the water circulation device configured as described above, when water is ejected from the ejection nozzle 7, water in the cylindrical space 6 is sucked in through the suction pipe 11 and mixed with water supplied from the cooling water vibrator 8 in the throat 12. and is discharged through the diff user 13. Residual stress is improved by heating the welded part 2 and its vicinity by heating means (for example, induction heating) 9 while cooling water is flowing in the space 6 to create a predetermined temperature distribution. In this case, air bubbles are generated in the water within the space 6 due to the heating.

Therefore, the conditions inside the space 6 in the conventional example and this embodiment will be explained while comparing them based on FIGS. 3 to 8.

In order to investigate the flow state in the space (narrow part) 6 of the conventional water circulation system shown in FIG. 9, FIG.

It is a diagram with symbols B, C, D, and H. Here, the O mark shown at position A represents the position of the jet nozzle 7 shown in FIG. It is considered that the curvature of the space 6 can be ignored for the fluid flowing through the space 6. Further, if it is assumed that the flow in planes A, B, D, and E is symmetrical, the flow in the space 6 can be analyzed two-dimensionally.

41st! l indicates the velocity vector in the non-heating state obtained as a result of the analysis. From Figure 4, even if the gap in the space 6 is small (the cooling water injected from A reaches the closed part of B, it flows from B to the lower part of C and D, and the cooling water flows through the space (narrow gap). Part) 6 flows out from the lower part E of the open side.The cooling method that generates this type of flow is suitable for cooling when no air bubbles are generated due to heating. As shown in , the flow 16 of cooling water in the heating section 17 is from the top to the bottom as shown by the solid line, whereas the direction of the buoyant force 15 due to the bubbles is from the bottom to the top as shown by the broken line. Therefore, if the amount of cooling water injected is small, the generated air bubbles cannot be removed sufficiently, and the air bubbles will accumulate in the upper part of the heating section 17, resulting in a film boiling state and achieving a predetermined temperature distribution. In order to avoid film boiling, it is necessary to inject a large amount of cooling water sufficient to overcome the buoyancy caused by the generation of bubbles.

On the other hand, the velocity vector analysis results for the cooling method of this embodiment are shown in FIG. 6. In the case of this cooling method, as shown in FIGS. 10 is installed to suck water from the closed side of the space 6 and inject water toward the open side, so fluid enters from the lower part E of the open side as shown by the arrows in FIGS. 2 and 6. , C, B, A flow occurs. Therefore, when air bubbles are generated, as shown in FIG. 7, the direction of the cooling water flow 16 in the heating section 17 and the buoyant force 15 due to the air bubbles are completely the same, so that the direction necessary to extract the air bubbles is Only a small amount of cooling water is required.Since the injection direction of the cooling water is from the closed side of the space 6 to the open side, the reaction that the water injection pump IO receives based on the momentum of the ejected water is due to the opening of the space 6. The direction is from the side to the closed side, and no special measures are required to fix the injection pump 10.

The velocity vector analysis results described above were compared with measured values using a plastic model to confirm their validity.

FIG. 8 shows the boiling state in the space 6 near the welding part 2, which was experimentally investigated by changing the water circulation device, and is expressed in terms of the relationship between the amount of water jetted from the jet nozzle 7 and the amount of heat input from the heating means 9. . The vertical axis is the heat input (g-p) required to form the temperature distribution required to improve the residual stress, which is rendered dimensionless, and the horizontal axis is the g 6 when water is circulated using the water circulation device (suction method) of this example. % is applied to change the water injection amount and the water injection amount changes from nucleate boiling to film boiling. The blowing method used in the conventional device is represented by a solid line curve IF, the blowing and suctioning method is represented by a dashed line curve G, and the upper suction method of the present invention is represented by a broken line curve H. In the case of the conventional blowing method, these are the results of experiments conducted with the jet nozzle securely fixed.As shown by these curves F, G, and H, the upper part shows film boiling, and the lower part shows nucleate boiling or boiling. This is a state that has not occurred.

From FIG. 8, it can be seen that the larger the amount of heat supplied and the smaller the amount of water injection, the easier it is to reach a film boiling state. It can be seen that film boiling can be prevented by changing the amount of water injected into the tank.

In the case of this device, since the water injection is performed from the closed side to the open side of the space 6, the water injection pump 10 tries to move in the opposite direction, that is, toward the space 6, but the movement prevention table 14C
Since its movement is restricted, stable water circulation continues.

Note that in order to obtain the above effect, the ratio (d/t) of the inner diameter (d) of the suction pipe 11 and the gap (1) of the space 6 should be set to 0.3 to 0.7. Found out experimentally.

[Effects of the Invention] As described above, according to the present invention, even if bubbles are generated due to heating, it is easy to extract the bubbles from the cooling water, and the water injection amount necessary to prevent film boiling can be reduced compared to the conventional device. Also to 1~
The residual stress can be reduced to about 88, and the residual stress can be efficiently improved by easily fixing the water injection nozzle and ensuring stable water circulation.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an embodiment of the water circulation device of the present invention;
Fig. 2 is an enlarged cross-sectional view of the main part of Fig. 1, Fig. 3 is an explanatory diagram with names given to each position in the space (narrow part), and Fig. 4 shows the flow state in the narrow part by the conventional device. Figure 5 shows the calculation results obtained by numerical analysis.1 Figure 5 is a diagram showing the relationship between the flow direction in the narrow part and the direction in which buoyancy acts in the conventional device, and Figure 6 shows the flow in the narrow part in the water circulation device of the present invention. Figure 7 shows the relationship between the direction of flow in the narrow space and the direction of buoyancy in the water circulation device of the present invention, and Figure 8 shows the results of calculations obtained by numerically analyzing the state. Figure 8 shows the water jet from the jet nozzle. Characteristic diagrams for determining the boiling state based on the relationship between the amount of water and the amount of heat input, FIG. 9 and FIG. 1O are cross-sectional views showing a conventional water circulation device. 1... Recirculation water artificial nozzle, 2... Welded part, 3... Safe end, 4... Base welded part, 5...・Thermal sleeve, 6...
... Space (narrow part), 7 ... Spout nozzle, 8 ... Cooling water pipe, 9 ... Heating means, 10 ... Water Injection pump, 11...
Suction tube, 12... Throat, 13...
Diff user, 14a, 14b, 14c...Movement prevention stand. Figure 1 Figure 2 Agent Masaru Nishimoto - Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 9 Figure 10 +9

Claims (3)

[Claims] (1) In a device that circulates water in a space that is closed at one end and open at the other end, water is spouted at the upper part of the open side of the space in a direction from the closed side to the open side of the space. A water circulation device characterized by being equipped with a water injection pump. (2) A water circulation device characterized in that a suction port of a suction pipe that communicates with the water injection pump and sucks water based on the water jet action thereof is installed toward the closed side of the space. (3) A ratio (d/t) between an inner diameter (d) of the suction pipe and a gap (t) of the space is 0.3 to 0.7. Water circulation device.